Abstract
Vitamin K is essential for blood coagulation and bone health. Menaquinone-4 (MK-4) and menaquinone-7 (MK-7) have been used as food supplements in Japan. In this study, to compare MK-4 and MK-7 metabolism, the minimal dose of vitamin K required for rats (1.1 nmol/g feed) was administered to rats for 21 days, and vitamin K levels in tissues were determined. Vitamin K_2 levels were much higher in the blood and liver of MK-7-fed rats than MK-4 fed-rats. MK-4 administration to rats did not increase the MK-4 levels in testis and femur. On the other hand, MK-4 was increased significantly in testis and femur of the MK-7-fed rats. These findings indicate that MK-7 is superior to MK-4 as a nutritional supplement.
